a. Field of the Invention
The present invention relates generally to boats having tubular flotation members and, more particularly, to a form of construction that allows tubular boats having a variety of lengths and configurations to be produced at reduced cost using modular components.
b. Background Art
Typically, small recreational boats are fabricated from fiberglass or aluminum in a rigid, open-hull configuration. The fiberglass versions generally require a dedicated mold designed specifically for each particular size and style of vessel. Because each mold is costly, and because the size of the molds requires a large facility for storage and production, the cost of producing a full line of boats which vary in size and configuration can quickly become exorbitant.
Traditional aluminum models face similar cost disadvantages. In some cases, the aluminum versions are hand fabricated using sheet metal forming and welding techniques. This is a costly, labor-intensive process that is usually only cost effective for custom boats. On the other hand, large-scale production requires large dedicated dies and jigs for forming and assembling the aluminum hull panels, resulting in cost and space requirements paralleling those associated with production of fiberglass boats using dedicated molds.
Regardless of materials and production methods, typical rigid, open-hulled boats have proven themselves effective for general recreational activities in calm waters. However, in more extreme conditions, such as shallow reefs and rocky coastlines, or during inclement weather conditions, these traditional configurations often lack the stability and sea-worthiness necessary for safe operation, and in particular retain minimal buoyancy when swamped. In response, numerous manufactures have developed boats having a rigid hull inflatable (RHIB) configuration as a safer alternative for harsh or difficult environments and operations.
Generally, a rigid-hull inflatable boat derives buoyancy and stability from U-shaped tubular collar, in which the bight of the “U” forms the bow and the trailing portions form gunwales that extend rearwardly to a transom at the stern of the assembly. A rigid hull, nested within and attached to the U-shaped collar, provides a hydrodynamic running surface for the craft as well as a support platform for the occupants. An outboard motor attached to the transom typically provides propulsion.
Although a variety of collar configurations can be found in the prior art, the most common configuration employs a flexible pneumatic bladder that is inflated with air. In addition to being easily transportable, the popularity of this configuration sterns from reduced costs in manufacturing, in that it does not require the dedicated molds and related expenses associated with traditional, open-hulled boat production.
To prevent catastrophic failure in the event of a puncture, the pneumatic bladders on such boats are commonly compartmentalized to form two or more chambers. Although this adds a degree of safety, a bladder failure can still strand the occupants or significantly reduce travel speed, creating a situation that is inconvenient at best and life threatening at worst. To overcome this deficiency, a few manufacturers have developed an improved form of boat this is similar to rigid-hull inflatable boats in overall configuration, but in which the collar is formed as a rigid or semi-rigid shell which is filled with a low density, closed cell, foam core. In the event of a puncture the core material prevents water from entering the chamber, so that stability and mobility remain substantially unimpaired until repairs can be made.
While RHIB-style boats with foam filled collars are among the most robust and seaworthy craft available, prior versions have generally required dedicated molds for construction of the rigid collar thus incurring expenses and difficulties similar to those discussed with regard to the production of traditional, open hulled boats. As a result, the introduction of each new model having significant dimensional changes has required a new, expensive, dedicated mold, imposing a significant cost burden on the manufacturer and ultimately the consumer.
Moreover, because RHIB-style boats derive their stability from the buoyant collar, the rigid floor/hull is typically mounted relatively high within the collar, so that the collar gunwales act somewhat as pontoons. This provides a high degree of stability and a smooth ride on calm waters, however, in rough conditions this configuration tends to pound the waves, which is detrimental to both stability and passenger comfort. An alternative is to provide the craft with more of a V-shaped hull/floor unit and position it deeper with respect to the collar, which provides a smoother ride and better seaworthiness in rough conditions by cutting through the waves, but at the expense of rendering the craft more “tippy” and less maneuverable under calm water conditions.
As is apparent, the two hull configurations are physically at odds with each other, each excelling under certain conditions. Consequently, the consumer would like the option to purchase the hull configuration most applicable to boating requirements. Unfortunately, the types of constructions used in prior RHIB-style boats are unable to accommodate both configurations without doubling the number of models offered and assuming the financial penalties associated with the additional molds and tooling.
Accordingly, there exists a need for a safe, stable, and affordable boat that cannot deflate, collapse or sink like other boats found in the prior art. Furthermore, there exists a need for such a boat that can be easily configured during manufacture with variations in length and hull shape, thus accommodating a wide range of consumer applications. Still further, there exists a need for such a boat in which such variations in length and hull configuration can be accomplished without requiring additional dedicated molds or tooling, thus reducing the cost of producing a full line of boats.